groups(1)

Name

groups– print group membership of user

Synopsis

groups [user]...

Description

The command groups prints on standard output the groups to which you or the optionally specified user belong. Each user belongs to a group specified in /etc/passwd
and possibly to other groups as specified in /etc/group. Note that /etc/passwd specifies the numerical ID (gid)
of the group. The groups command converts gid to the group name in the output.